Exemplary embodiments of the present disclosure relate to a transition part assembly and a combustor including the same, and more particularly, to a transition part assembly which is improved in efficiency of cooling a high-temperature region formed on a side surface of a transition part of a gas turbine, and a combustor including the same.
A turbine is a machine which generates rotating force from driving force or reaction force using the flow of compressive fluid such as gas. If steam is used, the turbine is called a steam turbine, and if combustion gas is used, it is called a gas turbine.
The gas turbine includes a compressor, a combustor and a turbine. The compressor sucks the atmospheric air, compresses it, and then supplies high-pressure air to the combustor. The combustor generates high-temperature and high-pressure combustion gas. The turbine is driven by combustion gas discharged from the combustor so as to rotate a rotating shaft. The operation principle of the gas turbine includes sucking the atmosphere air, compressing it using the compressor and transferring the compressed air to the combustor, generating high-temperature and high-pressure gas in the combustor, driving the turbine using the high-temperature and high-pressure gas, and then discharging exhaust gas to the atmosphere. In other words, the operation principle of the gas turbine includes a compression step, a heating step, an expansion step, and a heat dissipation step.
The compressor of the gas turbine functions to suck air from the atmosphere and supply air for combustion to the combustor. During an adiabatic compression process in the compressor, the pressure and temperature of air are increased. In the combustor, a constant-pressure combustion process is performed, during which drawn compressed air is mixed with fuel, and a mixture of the compressed air and fuel is combusted to produce combustion gas having high energy.
High-temperature and high-pressure combustion gas discharged from the combustor expands and applies driving force and reaction force to an impeller of the turbine, thus generating mechanical energy. Some of the mechanical energy is supplied as energy required for compressing air in the compressor, and the remaining mechanical energy is used to drive a generator so as to produce electric power.
The combustor of the gas turbine includes a liner unit and a transition part. The liner unit combusts fuel together with compressed air and produces high-temperature compressed gas. The high-temperature compressed gas is drawn into the turbine and expanded to rotate the rotating shaft coupled with the turbine. The transition part is used to transfer combustion gas generated from the combustor liner to the turbine and functions to increase the flow rate of high-temperature gas. The outer surface of the transition part is cooled by compressed air supplied from the compressor so as to prevent the transition part from being damaged by the high-temperature combustion gas.
For this, a perforated sleeve encloses the transition part and is configured such that air discharged from the compressor flows into the perforated sleeve through cooling holes formed in the perforated sleeve and comes into contact with the outer surface of the transition part so as to cool it. Cooling air that has been used to cool the outer surface of the transition part flows along space between the perforated sleeve and the transition part toward the liner unit.
The temperature distribution of the transition part when operating the gas turbine in the related art shows that a high temperature region is formed on the side surface of the transition part.
However, although the transition part is provided with the perforated sleeve enclosing the transition part, there is a problem in that the efficiency of cooling the transition part is not satisfied because a sufficient amount of cooling air is not supplied to the side surface of the transition part.
Therefore, the transition part is not effectively cooled, so that there is a risk of the transition part being damaged by high-temperature combustion gas, and the efficiency and lifetime of the gas turbine are reduced.